The invention relates to electrical cord connecting apparatus, and more particularly to an electrical receptacle with a releasable locking means for a plug, or cap.
Several types of locking electrical receptacles, for preventing accidental withdrawl of a cap from the receptacle when some tension is introduced into the electrical cords, have been suggested previously. For example, Carissimi et al U.S. Pat. No. 3,801,757 disclosed a connector having a releasable locking means that locked the heavy duty male connector to the receptacle through slots in the face of the receptacle, for safety purposes Bissell U.S. Pat. No. 2,015,543 suggested the use of a manually operated device that mechanically locked the male connector in place when inserted in the receptacle and also actuated a switch. This assured that power was off whenever the connectors were separated, so that arcing could not occur. There have also been designed special flanged cap blades and corresponding structure in a receptacle, such that the cap was pushed in and then twisted in a clockwise direction to lock it in place. This of course required replacement of both caps and receptacles by one who desired to change over to a locking system.
Graf U.S. Pat. No. 1,019,455 disclosed a locking device which utilized apertures in the prongs of the plug connector. The locking device was actuated by a switch knob on the receptacle.
None of the locking devices suggested in the prior art was as fast and efficient in operation, as safe, versatile, and as efficiently constructed as the improved locking receptacle described below.